104 Aquarii

This article is about A² Aquarii. For A¹ Aquarii, see 103 Aquarii. For all stars with the same Bayer designation, see A Aquarii.

104 Aquarii (abbreviated 104 Aqr) is a star in the equatorial constellation of Aquarius. 104 Aquarii is the Flamsteed designation, although it also bears the Bayer designation A² Aquarii. Based on an annual parallax shift of only 3.89 ± 0.25 milliarcseconds, the distance to this star is about 840 light-years (260 parsecs).^[9] At that range, the brightness of the star in the V-band is reduced by 0.10 magnitudes as a result of extinction caused by intervening gas and dust.^[5]

104 Aquarii

Observation data Epoch J2000      Equinox J2000
Constellation	Aquarius
A
Right ascension	23h 41m 45.80579s[1]
Declination	–17° 48′ 59.5175″[1]
Apparent magnitude (V)	4.83[2]
B
Right ascension	23h 41m 46.37788s[1]
Declination	–17° 47′ 00.7237″[1]
Apparent magnitude (V)	8.54[2]
Characteristics
A
Spectral type	G2 Ib/II[3]
U−B color index	+0.49[2]
B−V color index	+0.82[2]
B
Spectral type	A5/7 (V)[3]
B−V color index	+0.15[2]
Astrometry
A
Radial velocity (Rv)	+6.52±0.15[4] km/s
Proper motion (μ)	RA: +14.872[1] mas/yr Dec.: +0.862[1] mas/yr
Parallax (π)	4.5774 ± 0.1882 mas[1]
Distance	710 ± 30 ly (218 ± 9 pc)
Absolute magnitude (MV)	–2.49[4]
B
Proper motion (μ)	RA: –27.214[1] mas/yr Dec.: –28.539[1] mas/yr
Parallax (π)	3.2221 ± 0.0487 mas[1]
Distance	1,010 ± 20 ly (310 ± 5 pc)
Details
104 Aqr A
Mass	4.23[5] M☉
Radius	31.9±2.3[4] R☉
Luminosity	447[5] L☉
Surface gravity (log g)	2.20[4] cgs
Temperature	5,444±14[4] K
Metallicity [Fe/H]	+0.05[6] dex
Rotational velocity (v sin i)	15[7] km/s
Age	135[5] Myr
Other designations
HR 8982, SAO 165836.[8]
A: BD −18 6358, HD 222574, HIP 116901
B: BD −18 6359, HD 222561, HIP 116904
Database references
SIMBAD	data
	B

This is a double star and possible binary system.^[10] The primary component has a stellar classification of G2 Ib/II,^[3] which places it on the borderline between the bright giant and lower luminosity supergiant stars. It has passed the first dredge-up and may be undergoing Cepheid-like pulsations.^[4] With more than four times the mass of the Sun,^[5] this is an evolved star that has reached its current stage after only 135 million years.^[5] It has expanded to around 51–88^[11] times the Sun's radius and is radiating 447–fold^[5] the luminosity of the Sun. This energy is being emitted from its outer atmosphere at an effective temperature of 5,478 K,^[6] giving it the golden-hued glow of a G-type star.^[12] It is a suspected variable star.^[13]

The companion is a magnitude 7.9 star with an angular separation of 120.1 arcseconds from the primary.^[10]

References

1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
2. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
3. Houk, N.; Smith-Moore, M. (1988). "Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0". Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4. Bibcode:1988mcts.book.....H.
4. Usenko, I. A.; et al. (November 2015), "Spectroscopic studies of four southern-hemisphere G-K supergiants: HD 192876 (α1 Cap), HD 194215 (HR 7801), HD 206834 (c Cap), and HD 222574 (104 Aqr)", Astronomy Letters, 41 (11): 660–676, Bibcode:2015AstL...41..660U, doi:10.1134/S1063773715110067, S2CID 124555577.
5. Takeda, Yoichi; Sato, Bun'ei; Murata, Daisuke (2008), "Stellar Parameters and Elemental Abundances of Late-G Giants", Publications of the Astronomical Society of Japan, 60 (4): 781–802, arXiv:0805.2434, Bibcode:2008PASJ...60..781T, doi:10.1093/pasj/60.4.781.
6. Luck, R. E.; Bond, H. E. (October 1980), "The chemical compositions of 26 distant late-type supergiants and the metallicity gradient in the galactic disk", Astrophysical Journal, Part 1, 241: 218–228, Bibcode:1980ApJ...241..218L, doi:10.1086/158334.
7. Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1): 1, Bibcode:1970CoAsi.239....1B.
8. "104 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-16.
9. van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
10. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
11. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
12. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on February 22, 2012, retrieved 2012-01-16.
13. Demartino, Robert; et al. (April 1996), "Accurate Positions Of Suspected Variable Stars Near The South Galactic Pole", Information Bulletin on Variable Stars, 4322: 1, Bibcode:1996IBVS.4322....1D.

External links

• Image 104 Aquarii